This invention relates generally to cooling of electronic components and, more particularly to the cooling of electronic devices by heatsinks.
As is known in the art electronic components such as solid state devices dissipate power as heat. As the density and speed of modern solid state devices such as integrated circuits increases, the heat per area produced by these devices also increases. Without proper cooling of the solid state device junction temperatures of the device increase beyond the design specification which can result in thermal and chemical breakdown of the device.
One prior attempt to cool such devices was to place the components in a computer cabinet which was cooled by fans mounted in the cabinet and disposed so they would blow air across a circuit board on which the components were mounted. Often these components had passive heatsinks attached to the devices which dissipated high amounts of power. This passive heatsinking solution is inadequate for those applications requiring components which now dissipate more power than can be effectively cooled in this manner.
Previous attempts to cool higher power components by an active means have included employing liquid nitrogen cooling for the entire circuit board, the use of a self-contained evaporator and condenser apparatus coupled directly to the component or the positioning of a tube axial fan directly over a conventional heatsink directly coupled to the component. All of these implementations suffer serious drawbacks. The liquid nitrogen cooling is expensive, requires additional space and plumbing and lowers the mean time between failures of the system. The use of a self-contained evaporator and condenser apparatus also suffers from being expensive to implement as well as requiring additional space.
On the other hand the use of a tube axial fan mounted directly to a conventional heatsink, while effective for earlier applications, suffers from having it's lowest thermal resistance at the periphery of the heatsink, rather than the center of the heatsink where most of the component's power is actually dissipated. This problem results from having low airflow velocities directly behind the hub of the tube axial fan which is located over the center of the heatsink. In operation of such a heatsink arrangement the motion of the fan blades of the fan provide a wake or disturbance around the center hub which mitigates the amount of air flow available at the center of the fan heatsink assembly. Since the center of the heatsink is located over the hottest part of the component and is located in the lowest air flow part of the fan, the wake produced by the center hub of the tube axial fan, the heatsink performance of this implementation is degraded. The cooling actually takes place at the periphery of the heatsink resulting in a low overall efficiency because the heat is now spread along the outer edges fins in order to be effectively cooled.